Withdrawable devices housed within a medium-voltage switchgear framework are periodically disconnected for maintenance, testing or replacement. This disconnection of the withdrawable device from the switchgear is known as “racking out”. Connection of the withdrawable device to the switchgear is known as “racking in”.
Manual racking of a withdrawable device is labor intensive and dangerous due to the potential for an arc flash. The operator who performs the manual racking must wear bulky personal protective equipment (PPE) while conducting the racking operation to prevent injury or death, should an arc flash occur. An arc flash occurs when electric current passes through the air between ungrounded conductors or between ungrounded conductors and grounded conductors. Arc flashes are fatal within a distance of ten feet and cause severe burns due to the extreme temperatures. Motorized racking equipment is available, but is heavy and difficult to align with a switchgear cabinet, requiring lifting equipment and meticulous alignment steps.